Hi there does anyone know how the speedometer part of the dash is connected to the rest of the wiring?
Does it work via OBD datalink connection like the tacho, or by some other method?
BTW I am not talking about the common Focus VSS gearbox sensor problem - it's about understanding how the speedo works.

Someone must have sorted this out if they used an aftermarket engine ECU such as Megasquirt on the standard Ford dash